FIG. 1B shows a cross-sectional view of a right angle fluid end for use in a typical pump known from the prior art. The section is taken along view line A-A of FIG. 1A. The cross-bore intersection of the fluid end is commonly subjected to high stresses. The fluid end 10 shown in FIGS. 1A and 1B has a power end bore 12, suction bore 13, and discharge bore 14. The fluid end 10 also has a valve cover bore 15 which can also be called an access bore. Transitional surface open areas 12a, 13a, 14a, and 15a open into the cross-bore intersection 16. Each of the transition open areas 12a, 13a, 14a, and 15a are delimited by transition surfaces 12b, 13b, 14b and 15b. As seen in FIG. 1B, the transition surfaces 12b and 15b have intersecting edges and form non-uniform curves.
U.S. Pat. No. 6,910,871 to Blume discloses valve guide and spring retainer assemblies for use in plunger pump housings that incorporate features for stress relief. Blume introduces large chamfers in the pump housing. The cross-bore intersection has an elongated cross-section.
U.S. Pat. No. 6,544,012 to Blume discloses a Y-block fluid section of a plunger pump having a bore which is transversely elongated at its intersection with suction and discharge bores to provide stress relief and reduction in housing weight. A spoked, ring valve spring retainer further reduces stress near the bore intersection and allows use of a top stem guided suction valve.